Electromagnetic induction

Electromagnetic induction has countless applications for science, technology and society, such as electric current generators, transformers, induction furnaces, certain controls and magnetic “brakes”, etc.


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  • 1 electromagnetic induction
  • 2 Lenz’s Law
  • 3 Faraday’s Law
  • 4 factors on which the emf or induced current depends
  • 5 See also
  • 6 Sources

Electromagnetic induction

Michael Faraday conducted experiments on electromagnetic induction, discovered that a moving conductor can cut the lines of force of a magnetic field and an induced electromotive force (emf) originates and in a closed circuit an induced current would originate. The same would happen if the magnetic flux through the conductor is variable.

Lenz’s Law

Lenz’s law is used to determine the direction of the induced current and states that:

The induction current, in all cases, has a meaning such that its effect is opposed to the cause that originates it.

To understand this law well, two key words should be highlighted>

  • Cause: The cause of all induced current is the variation of the magnetic induction flux ΦB.
  • Effect: the effect of the induced current is the field. magnetic associated with it.

Faraday’s Law

The induced emf ε i in a closed circuit is equal in modulus to the speed with which the magnetic flux through the area limited by the circuit varies:

This expression does not fully describe the phenomenon of electromagnetic induction, since it does not take into account the number of turns and the behavior of the induced current. For this, the following equation must be used:

where the negative sign reflects the fact that the polarity of the emf is such that the current it produces determines a magnetic field that opposes the variation of the magnetic induction flux, N is the number of turns (or turns) of the coil, ΔΦ B is the flux variation, Δt is the time variation and the term:

It is known as the speed with which the magnetic flux varies through the area limited by the circuit.

The unit of measurement of the emf in the International System of Measurements (SI) is the volt (V).

Factors on which the emf or induced current depends

  • Number of turns (turns): increasing the number of turns increases the induced current
  • Magnetic induction: increasing Magnetic induction (larger magnet) increases the induced current.
  • Coil Cross Section Area: Increasing the cross section area increases the induced current.
  • Magnet Movement Speed: Increasing the Magnet Movement Speed ​​increases the induced curren


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